Magnetic pressure support and accretion disk spectra

Omer M. Blaes, Shane W. Davis, Shigenobu Hirose, Julian H. Krolik, James McLellan Stone

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41 Scopus citations


Stellar atmosphere models of ionized accretion disks have generally neglected the contribution of magnetic fields to the vertical hydrostatic support, although magnetic fields are widely believed to play a critical role in the transport of angular momentum. Simulations of magnetorotational turbulence in a vertically stratified shearing box geometry show that magnetic pressure support can be dominant in the upper layers of the disk. We present calculations of accretion disk spectra that incorporate vertical magnetic pressure and dissipation profiles derived from the radiation magnetohydrodynamical simulation of Hirose, Krolik, & Stone. Magnetic pressure support generically produces a more vertically extended disk atmosphere with a larger density scale height. This acts to harden the spectrum compared to models that neglect magnetic pressure support. We estimate the significance of this effect on disk-integrated spectra by calculating an illustrative disk model for a stellar mass black hole, assuming that similar magnetic pressure support exists at all radii.

Original languageEnglish (US)
Pages (from-to)1402-1407
Number of pages6
JournalAstrophysical Journal
Issue number2 I
StatePublished - Jul 10 2006

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


  • Accretion, accretion disks
  • MHD
  • Radiative transfer
  • X-rays: binaries


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